Improvement in the art of manufacturing cast-iron cannon



H v p UNITED STATES PATENT. ()FFIQE.

CYRUS ALGER, OF BOSTON, MASSAOHUSETTSI Specification forming part of Letters Patent No. 208, dated May 30, 1837.

To all whom it may concern:

Be it known that I, CYRUS ALGER, of the city of Boston, in the State of Massachusetts, have invented an Improvement in the art of Manufacturing Cast-Iron Gannon, by means of which improvement such guns are rendered much more tenacious and less liable to be injured in the here by the discharges of the ball than those made upon the plans heretofore pursued; and I do hereby declare that the following is a full and exact description thereof.

1 cast and bore the cannon or gun in the usual way, taking care, however, that the bore is somewhatless than theintended caliber, for a reason to be presently explained. I then anneal it by the known process of rendering cast-iron malleable, when it'will be found that the here has actually enlarged, and in a six-pounder to the extent of about one-sixteenth of an inch in diameter. This enlargementisinconsequence of time as may be necessary, depending upon the depth to whichit is desired that the hardening should extend. I then discharge the hardening and apply eold water under a sutficient head, so as suddenly to cool and consesequently to harden the interior.

1 do not claim to be the-inventor of the'process for rendering cast-iron malleable, nor of that of case-hardening malleable iron; but I What I do claim as my invention, and not heretofore used or known, is-

The improvement in the manufacture of castiron cannon by the combined process of annealing and hardening, as herein described.

CYR US A LGER. Witnesses:

\ SAMUEL L. RIDGWAY,

H. MONTGOMERY. 

